Commit 1c5d0fc4 authored by Marc Kleine-Budde's avatar Marc Kleine-Budde
Browse files

can: tcan4x5x: rework SPI access 



This patch reworks the SPI access and fixes several probems:
- tcan4x5x_regmap_gather_write(), tcan4x5x_regmap_read():
  Do not place variable "addr" on stack and use it as buffer for SPI
  transfer. Buffers for SPI transfers must be allocated from DMA save
  memory.
- tcan4x5x_regmap_gather_write(), tcan4x5x_regmap_read():
  Halfe number of SPI transfers by using a single buffer + memcpy().
  This improves the performance, especially on SPI controllers, which
  use interrupt based transfers.
- Use "8" bits per word, not "32". This makes it possible to use this
  driver on SoCs like the Raspberry Pi, which SPI host controller
  drivers only support 8 bits per word.

Note: this breaks half duplex only controllers. Support for them will be
re-added in the next patch.

Reviewed-by: default avatarDan Murphy <dmurphy@ti.com>
Tested-by: default avatarSean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-16-mkl@pengutronix.de


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 1e81d525

drivers/net/can/m_can/tcan4x5x-core.c

+1 −1
Original line number Diff line number Diff line
@@ -380,7 +380,7 @@ static int tcan4x5x_can_probe(struct spi_device *spi) 
	spi_set_drvdata(spi, priv);



	/* Configure the SPI bus */

	spi->bits_per_word = 32;

	spi->bits_per_word = 8;

	ret = spi_setup(spi);

	if (ret)

		goto out_m_can_class_free_dev;

drivers/net/can/m_can/tcan4x5x-regmap.c

+60 −27
Original line number Diff line number Diff line
@@ -9,48 +9,76 @@ 


#include "tcan4x5x.h"



#define TCAN4X5X_WRITE_CMD (0x61 << 24)

#define TCAN4X5X_READ_CMD (0x41 << 24)

#define TCAN4X5X_SPI_INSTRUCTION_WRITE (0x61 << 24)

#define TCAN4X5X_SPI_INSTRUCTION_READ (0x41 << 24)



#define TCAN4X5X_MAX_REGISTER 0x8ffc



static int tcan4x5x_regmap_gather_write(void *context, const void *reg,

					size_t reg_len, const void *val,

					size_t val_len)

static int tcan4x5x_regmap_gather_write(void *context,

					const void *reg, size_t reg_len,

					const void *val, size_t val_len)

{

	struct spi_device *spi = context;

	struct spi_message m;

	u32 addr;

	struct spi_transfer t[2] = {

		{ .tx_buf = &addr, .len = reg_len, .cs_change = 0,},

		{ .tx_buf = val, .len = val_len, },

	struct tcan4x5x_priv *priv = spi_get_drvdata(spi);

	struct tcan4x5x_map_buf *buf_tx = &priv->map_buf_tx;

	struct spi_transfer xfer[] = {

		{

			.tx_buf = buf_tx,

			.len = sizeof(buf_tx->cmd) + val_len,

		},

	};



	addr = TCAN4X5X_WRITE_CMD | (*((u16 *)reg) << 8) | val_len >> 2;



	spi_message_init(&m);

	spi_message_add_tail(&t[0], &m);

	spi_message_add_tail(&t[1], &m);

	memcpy(&buf_tx->cmd, reg, sizeof(buf_tx->cmd.cmd) +

	       sizeof(buf_tx->cmd.addr));

	tcan4x5x_spi_cmd_set_len(&buf_tx->cmd, val_len);

	memcpy(buf_tx->data, val, val_len);



	return spi_sync(spi, &m);

	return spi_sync_transfer(spi, xfer, ARRAY_SIZE(xfer));

}



static int tcan4x5x_regmap_write(void *context, const void *data, size_t count)

{

	return tcan4x5x_regmap_gather_write(context, data, sizeof(u32),

					    data + sizeof(u32),

					    count - sizeof(u32));

	return tcan4x5x_regmap_gather_write(context, data, sizeof(__be32),

					    data + sizeof(__be32),

					    count - sizeof(__be32));

}



static int tcan4x5x_regmap_read(void *context,

				const void *reg, size_t reg_size,

				void *val, size_t val_size)

				const void *reg_buf, size_t reg_len,

				void *val_buf, size_t val_len)

{

	struct spi_device *spi = context;

	struct tcan4x5x_priv *priv = spi_get_drvdata(spi);

	struct tcan4x5x_map_buf *buf_rx = &priv->map_buf_rx;

	struct tcan4x5x_map_buf *buf_tx = &priv->map_buf_tx;

	struct spi_transfer xfer[] = {

		{

			.tx_buf = buf_tx,

		}

	};

	struct spi_message msg;

	int err;



	spi_message_init(&msg);

	spi_message_add_tail(&xfer[0], &msg);



	u32 addr = TCAN4X5X_READ_CMD | (*((u16 *)reg) << 8) | val_size >> 2;

	memcpy(&buf_tx->cmd, reg_buf, sizeof(buf_tx->cmd.cmd) +

	       sizeof(buf_tx->cmd.addr));

	tcan4x5x_spi_cmd_set_len(&buf_tx->cmd, val_len);



	return spi_write_then_read(spi, &addr, reg_size, (u32 *)val, val_size);

	xfer[0].rx_buf = buf_rx;

	xfer[0].len = sizeof(buf_tx->cmd) + val_len;



	if (TCAN4X5X_SANITIZE_SPI)

		memset(buf_tx->data, 0x0, val_len);



	err = spi_sync(spi, &msg);

	if (err)

		return err;



	memcpy(val_buf, buf_rx->data, val_len);



	return 0;

}



static const struct regmap_range tcan4x5x_reg_table_yes_range[] = {
@@ -66,21 +94,26 @@ static const struct regmap_access_table tcan4x5x_reg_table = { 
};



static const struct regmap_config tcan4x5x_regmap = {

	.reg_bits = 32,

	.reg_bits = 24,

	.reg_stride = 4,

	.pad_bits = 8,

	.val_bits = 32,

	.wr_table = &tcan4x5x_reg_table,

	.rd_table = &tcan4x5x_reg_table,

	.cache_type = REGCACHE_NONE,

	.max_register = TCAN4X5X_MAX_REGISTER,

	.cache_type = REGCACHE_NONE,

	.read_flag_mask = (__force unsigned long)

		cpu_to_be32(TCAN4X5X_SPI_INSTRUCTION_READ),

	.write_flag_mask = (__force unsigned long)

		cpu_to_be32(TCAN4X5X_SPI_INSTRUCTION_WRITE),

};



static const struct regmap_bus tcan4x5x_bus = {

	.write = tcan4x5x_regmap_write,

	.gather_write = tcan4x5x_regmap_gather_write,

	.read = tcan4x5x_regmap_read,

	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,

	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,

	.reg_format_endian_default = REGMAP_ENDIAN_BIG,

	.val_format_endian_default = REGMAP_ENDIAN_BIG,

	.max_raw_read = 256,

	.max_raw_write = 256,

};

drivers/net/can/m_can/tcan4x5x.h

+23 −0
Original line number Diff line number Diff line
@@ -17,6 +17,19 @@ 


#include "m_can.h"



#define TCAN4X5X_SANITIZE_SPI 1



struct __packed tcan4x5x_buf_cmd {

	u8 cmd;

	__be16 addr;

	u8 len;

};



struct __packed tcan4x5x_map_buf {

	struct tcan4x5x_buf_cmd cmd;

	u8 data[256 * sizeof(u32)];

} ____cacheline_aligned;



struct tcan4x5x_priv {

	struct m_can_classdev cdev;
@@ -27,8 +40,18 @@ struct tcan4x5x_priv { 
	struct gpio_desc *device_wake_gpio;

	struct gpio_desc *device_state_gpio;

	struct regulator *power;



	struct tcan4x5x_map_buf map_buf_rx;

	struct tcan4x5x_map_buf map_buf_tx;

};



static inline void

tcan4x5x_spi_cmd_set_len(struct tcan4x5x_buf_cmd *cmd, u8 len)

{

	/* number of u32 */

	cmd->len = len >> 2;

}



int tcan4x5x_regmap_init(struct tcan4x5x_priv *priv);



#endif